title: Outbreak in a haematology unit involving an unusual strain of glycopeptide-resistant Enterococcus faecium carrying both vanA and vanB genes.
abstract: OBJECTIVE
  To report an outbreak due to an unusual strain of Enterococcus faecium containing both the vanA and vanB genes, in France, where the rate of glycopeptide-resistant enterococci (GRE) is below 1%.
  
  
  METHODS
  Cases were patients infected or colonized with GRE on the haematology ward. Contact patients were screened by real-time PCR performed on rectal swabs. Clinical features were compared for GRE-positive and GRE-negative patients. GRE isolates were characterized by phenotypic and molecular methods including PFGE. Conjugation experiments were performed to identify van genetic support.
  
  
  RESULTS
  After the index patient presented a bacteraemia with vanA/vanB E. faecium, 56 contact patients were screened, 7 of whom were found to be GRE positive: 6 additional cases with vanA/vanB E. faecium and 1 with GRE carrying vanA only. PFGE confirmed the clonal relationship of the seven vanA/vanB E. faecium strains, whereas the vanA isolate was distinct. Only the vanA gene could be transferred to enterococcal recipients by conjugation, and it was probably localized on a mobile genetic element. All isolates were resistant to vancomycin (MIC > 256 mg/L) and teicoplanin (MIC = 24-32 mg/L), but were susceptible to tigecycline (MIC = 0.09 mg/L), linezolid (MIC = 0.75 mg/L) and daptomycin (MIC = 1-2 mg/L). Significant differences (P < 0.001) between carriers and non-carriers of GRE were observed for the median duration of hospitalization (57 days versus 16.5 days) and of neutropenia (40 days versus 6 days), the median number of antibiotics used (5 versus 1.5) and the duration of glycopeptide treatment (14.5 days versus 0 days).
  
  
  CONCLUSIONS
  vanA/vanB E. faecium strains, although rare, can emerge in the absence of previous outbreaks of vanA-GRE or vanB-GRE.
authors.affiliation: APHP, Hôpital Lariboisière, service de Bactériologie, Paris, France.
authors.forename: G
authors.initials: G
authors.lastname: Marcadé
authors.forename: J-B
authors.initials: JB
authors.lastname: Micol
authors.forename: H
authors.initials: H
authors.lastname: Jacquier
authors.forename: L
authors.initials: L
authors.lastname: Raskine
authors.forename: J-L
authors.initials: JL
authors.lastname: Donay
authors.forename: S
authors.initials: S
authors.lastname: Nicolas-Viaud
authors.forename: M
authors.initials: M
authors.lastname: Rouveau
authors.forename: P
authors.initials: P
authors.lastname: Ribaud
authors.forename: H
authors.initials: H
authors.lastname: Dombret
authors.forename: R
authors.initials: R
authors.lastname: Leclercq
authors.forename: E
authors.initials: E
authors.lastname: Cambau
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D019729:Carbon-Oxygen Ligases / Q000235:genetics*; D004196:Disease Outbreaks; D016984:Enterococcus faecium / Q000235:genetics* / Q000378:metabolism; D005602:France / Q000453:epidemiology; D006020:Glycopeptides / Q000494:pharmacology* / Q000627:therapeutic use; D006402:Hematologic Diseases / Q000188:drug therapy / Q000453:epidemiology / Q000235:genetics*; D006757:Hospital Units; D006801:Humans; D020713:Vancomycin Resistance / Q000187:drug effects / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D006020:Glycopeptides; C071437:VanA ligase, Bacteria; C079913:VanB protein, Enterococcus; D019729:Carbon-Oxygen Ligases
keywords: GeneXpert VRE® assay; contact precautions; febrile neutropenia; nosocomial infections; vancomycin-resistant enterococci